Re: C vs C++

[CRPence <CRPbottle@xxxxxxxxx>]

On 16-Feb-2015 08:56 -0600, Jevgeni Astanovski wrote:
> Does anyone have any idea why C++ program is significantly slower than
> C program?
>
> Explain the situation.
> I have a number of APIs that are called via RPC, access some tables,
> make some calculations and return some structures to the caller.
> They've all been written on ILE/C.
> Recently I started to experiment with porting them to ILE/C++.
> <<SNIP>>
>
> What I saw is that time increase looks like it has a proportional
> nature. I tested API in 3 cases (number of tests is over 100):
> simple request, medium request; complicated request
>
> and the timing is:
>  • Simple C: 1ms; Simple C++ : 2ms
>  • Medium C: 3ms; Simple C++ : 7ms
>  • Long C: 25ms; Long C++: 60ms.
>
> The difference is in number of records read from table and a number
> of calculations.  That is, a
>  • simple one retrieves less that 10 records;
>  • medium - more than 10 and
>  • long - more than 100. Program makes a lot of calculations
> with packed decimal.
>
> Any idea why it is like that

  Followups determined the issue is apparently for the calculations 
using the Packed BCD numeric data type using the C++ libraries.

> and is there anything that can be done about it?

  With so few specifics of the scenario, the following may be way off 
the mark, but as a possibility:

  Perhaps the /calculations with packed decimal/ over data that is 
apparently /record data/ of /some tables/ could be performed by the SQL?